Messages in this thread | | | Date | Sat, 14 Sep 2013 16:42:56 +0800 | From | Li Zefan <> | Subject | Re: [PATCH 1/2] [RFC v2] seqcount: Add lockdep functionality to seqcount/seqlock structures |
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On 2013/9/14 8:19, John Stultz wrote: > Currently seqlocks and seqcounts don't support lockdep. > > After running across a seqcount related deadlock in the timekeeping > code, I used a less-refined and more focused varient of this patch > to narrow down the cause of the issue. > > This is a first-pass attempt to properly enable lockdep functionality > on seqlocks and seqcounts. > > Since seqcounts are used in the vdso gettimeofday code, I've provided > lockdep accessors. > > I've also handled one cases where there were nested seqlock writers > and there may be more edge cases. > > Comments and feedback would be appreciated! >
Could you describe how seqlocks/seqcounts can lead to deadlock in the changelog?
> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> > Cc: Li Zefan <lizefan@huawei.com> > Cc: Steven Rostedt <rostedt@goodmis.org> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Ingo Molnar <mingo@kernel.org> > Cc: Thomas Gleixner <tglx@linutronix.de> > Signed-off-by: John Stultz <john.stultz@linaro.org> > --- > v2: > * Update to new simplified lockdep.h > * vdso accessor simplifications > * removed needless preempt_disable > * removed unneeded ifdefs
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